Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M3/00—Automatic or semi-automatic exchanges
  • H04M3/22—Arrangements for supervision, monitoring or testing
  • H04M3/36—Statistical metering, e.g. recording occasions when traffic exceeds capacity of trunks

Definitions

• the present invention relates to a method and apparatus for performing a traffic measurement in a telecommunication network, like a public switched telephone network (PSTN) or a public land mobile network (PLMN) .
• a telecommunication network like a public switched telephone network (PSTN) or a public land mobile network (PLMN) .
• PSTN public switched telephone network
• PLMN public land mobile network
• the telephone traffic is defined as the aggregate of telephone calls over a group of circuits or trunks with regard to their durations of the calls as well as there numbers.
• Traffic flow through a switch or trunk group is defined as the product of the number of calls during a period of time and their average holding times. In traffic theory, the unit of time is one hour. Let C be the number of calls originated in one hour, and T be the average holding time, then the traffic flow intensity A is calculated on the basis of the following equation:
• ther. ths traffic intensity is:
• the international unit of telephone traffic is called "erlang", named after the Danish mathematician A. K. Erlang, founder of the theory of telephone traffic.
• Unit Call or its synonym "Centium Call-Second", abbreviated CCS is generally used.
• the traffic intensity is:
• the average number of busy trunks between Atlanta and Los Angeles has just increased to 16.67 from 10, because the average subscriber holds a conversation 2 minutes longer.
• a sampling method is used. According to this method, traffic samples are taken continuously. The traffic intensity corresponds to the average value of these samples .
• Fig. 2 shows a time diagram used for explaining the known traffic measurement.
• the measurement is performed on the basis of counters for counting predetermined parameters used for calculating the resultant traffic.
• counters are used for a current sample amount sa, an previous sample amount sap, an instantaneous load Id, a cumulative load lc and a previous cumulative load lcp.
• the measurement starts and the counters are initialized.
• the first reporting is performed and the traffic intensity is calculated according to the following equation:
• tr denotes the calculated traffic in erlang.
• the correct traffic value is 2.133 erlang.
• the calculation error is -6.7 % .
• the correct traffic value is 0.667 erlang, such that the error is -7.0 %.
• the accuracy of the measurement as well as the load of a CPU performing the traffic calculation is obviously dependent on the sampling period. If the sampling period is short, accuracy and CPU load are both increased. However, if the sampling period is long, the accuracy will decrease so that short calls between samples will not be registered at all. In practice, a default sampling period is set to 36 seconds.
• Another known method of performing traffic measurement is a time-based method used for example in a mobile exchange MSC (Mobile Switching Center) of a PLMN. This method is based on an object reservation time. A start time and a stop time of every call is stored. From these times, the total reservation time can be calculated. The traffic value or intensity is calculated by dividing the total reservation time by the accumulation period.
• MSC Mobile Switching Center
• time-based traffic measurement is explained on the basis of the call distribution shown ir. Fig. 2, wherein the measurement starts at 12:15:00 and the result accumulation period is 15 minutes.
• the call 2 starts at 12:18:00, such that the start time cf call 2 is set to 12:18:00.
• call 3 starts at 12:22:00 and a corresponding start time is registered for call 3.
• the call 3 is released and a corresponding stop time of call 3 is registered.
• a corresponding total reservation time or cumulative time tc is determined according to the equation:
• the first reporting and traffic intensity measurement is performed according to the following equation:
• tc indicates the current cumulative time
• tcp the previous cumulative time
• trp the previous report time
• trc the current report time
• call 1 is released and the corresponding stop time is registered.
• the error amounts to +7.9 % (correct value is 1.667 erlang).
• the error amounts to +220%, since the correct traffic value is 0.667 erlang.
• this known time- based method leads to the disadvantage that the calls are not registered until they are released. Moreover, calls are reserved before the measurement start will effect the traffic values.
• This object is achieved by a method for performing a traffic measurement in a telecommunication network, comprising the steps of: determining a cumulative total reservation time of a measurement object each time a traffic state of the object changes, and calculating a traffic value by dividing a change of the determined cumulative total reservation time by a corresponding time period.
• an apparatus for performing a traffic measurement in a telecommunication network comprising: means for determining a cumulative total reservation time of an object to be measured, control means for controlling the determining means so as to update the cumulative total reservation time each time a traffic state of the object changes, and calculating means for calculating a traffic value by dividing a change of the cumulative total reservation time by a corresponding time period.
• the cumulative total reservation time is determined each time a traffic state of the object changes, updating of the counters for calculating the traffic value can be done at any time regardless whether the traffic state of the object has changed or not.
• a correct cumulative total reservation time is always available such that exact and realtime traffic values can be obtained at any time of reporting.
• the calculation of the traffic value is performed when a traffic report is issued, wherein the corresponding time period is a time period since the last traffic report.
• the total reservation time may be determined by multiplying a value of an instantaneous load by a time period since the last determination of the cumulative total reservation time, wherein the value of the instantaneous load is updated each time the traffic state of the object changes.
• the traffic state change of the object may correspond to a call reservation or a call release.
• said object to be measured is an exchange switch.
• the determining means may comprise a counting means for counting the instantaneous load, a previous updating time, a current time, the cumulative total reservation time, a previous cumulative total reservation time and a last report time, wherein the calculation means is arranged to read the counting means and to calculate the change of the cumulative total reservation time by subtracting a read value of the previous cumulative total reservation time from a read value of the cumulative total reservation time, and the corresponding time period by subtracting a read value of the last report time from a read value of the current time.
• the determining means determines the cumulative total reservation time by reading the counting means and by multiplying a read value of the instantaneous load by a difference between a read value of the current time and a read value of the previous updating time.
• the counting means may be updated, when a traffic report is requested .
• a clock system may be provided for supplying a clock and for notifying the counting means of a clock change.
• Fig. 1 shows a block diagram of an apparatus for performing a traffic measurement according to a preferred embodiment of the present invention
• Fig. 2 shows a time diagram used for explaining a method for performing traffic measurement according to the preferred embodiment of the present invention.
• FIG. 1 A preferred embodiment of the present invention is shown in Fig. 1, wherein an exchange switch 3 of a telecommunication switching network is connected to a central processing unit (CPU) 4 of a means 1 for measuring a value of the traffic switched by the exchange switch 3. The measurement or calculation of the traffic value is performed on the basis of parameter values obtained from counting means 51-56 controlled or updated by the CPU 4.
• CPU central processing unit
• the counting means 51-56 are increased by the CPU 4 each time a change of the traffic switched by the exchange switch 3 occurs. Such a change is, for example, a release of a switched call or a reservation of a new call. Based on predetermined parameter values obtained from the counting means 51-56, the CPU 4 calculates a traffic intensity value on the basis of a control program at predetermined result accumulation periods and reports the obtained result to an operator of the exchange switch 3 or stores the result in a corresponding file or data base.
• the counting means comprises a plurality of counters 51-56 used for updating predetermined parameter values required for calculating the value of the traffic intensity or load.
• registers could be used instead of the counters, wherein the predetermined parameter values are calculated as such by the CPU 4 and stored in the corresponding register.
• the counting means 51-56 comprises a counter 51 used for updating a last report time which is the time of calculation and reporting of the last traffic intensity value.
• a counter 52 is provided for updating an instantaneous load which defines the current number of calls switched by the exchange switch 3.
• a counter 53 is provided for updating a previous updating time which is a time where the last update of the traffic load of the exchange switch 3 has occurred, i.e. due to a call reservation or a call release.
• a counter 54 for updating a current time is provided, wherein the current time is used to indicate a time of a current traffic state change of the exchange switch 3.
• counters 55 and 56 are provided for updating a total reservation time and a previous total reservation time, respectively, wherein the total reservation time indicates a value obtained by accumulating reservation times whenever a traffic report or a traffic change at the exchange switch 3 occurs.
• the reservation time is determined by multiplying the current instantaneous load by a time period since the last updating of the counters, i.e. since the last traffic report or traffic change of the exchange switch 3.
• the previous cumulative total reservation time corresponds to the cumulative total reservation time obtained before the last update.
• the cumulative total reservation time always correctly reflects the traffic history of the exchange switch 3, regardless of the result accumulation period or reporting period.
• a real-time traffic measurement is performed based on a total reservation time calculation of the exchange switch 3, each time the traffic state is changed.
• any circuit of a circuit group could be measured, wherein a state change could be a circuit reserving or releasing.
• each process requires an own counter 51 for counting the last report time.
• the remaining counters 52-56 can than be used in common.
• a clock system 2 can be provided for supplying a clock to the CPU 4, wherein an exchange clock back forwarding or forwarding, e.g. summer time setting, must be handled.
• the clock system 2 must notify the CPU 4 or the time counters 53- 56, so that the right past time can be calculated. Otherwise the traffic values would be wrong.
• a run over or overflow of the counters 51-56 must be handled. This can be achieved by detecting, whether a current counter value is less than an old value, which indicates that an overflow has occurred. This can be done by a control program performed by the CPU 4.
• a control program performed by the CPU 4.
• Id indicates the instantaneous load, tcu the current time, tup the previous updating time, tres the cumulative total reservation time, tresp the previous cumulative total reservation time, and trep the last report time.
• time values e.g. 12:15:00
• corresponding conversion routines are used by the CPU 4 for obtaining respective time differences .
• the first traffic change occurs, since call 2 is beginning and the counters are updated correspondingly.
• the first calculation and reporting of the traffic intensity value takes place at 12:30:00.
• the cumulative total reservation time and the corresponding traffic intensity amount to:
• the next change of the traffic state occurs at 12:40:00, since call 1 is released and the counters are updated in the following manner:
• the period from the beginning of call 1 to the start time of the measurement has no effect on the first report of the traffic intensity. Since any change of the traffic state is taken into account, the traffic intensity values are exactly right in all reports.
• a method and apparatus for performing a traffic measurement in a telecommunication network wherein a real-time traffic intensity measurement is based on a total reservation time calculation cf an object each time the traffic state of the object is changed.
• the object can be any circuit of a circuit group and the state change car De a circuit reservation or release. Since the total reservation time is calculated at any state change of the object, state changes are considered regardless of the actual reporting time. Thus, exact and real-time traffic intensity values can be obtained.

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• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Monitoring And Testing Of Exchanges (AREA)
• Data Exchanges In Wide-Area Networks (AREA)

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• 1998
  • 1998-07-22 AU AU89785/98A patent/AU8978598A/en not_active Abandoned
  • 1998-07-22 WO PCT/EP1998/004589 patent/WO2000005864A1/en not_active Application Discontinuation
  • 1998-07-22 EP EP98941400A patent/EP1099333A1/de not_active Withdrawn
• 2001
  • 2001-01-09 US US09/757,873 patent/US6674847B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

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